Can I have 4 LTMs in a cluster? 2 LTMs in one DC and 2 in another. Looking for active/active load balancing in 2 DCs. Looking for options. I can see documentation on 2 devices in Cluster.
Any one implemented F5 for active/active between DCs?
Appreciate your inputs,
As for v11.4 capabilities here are the release notes that talk to that feature
"Connection mirroring for device groups:
Prior to this release, you could only implement connection mirroring between a static pair of BIG-IP devices. Now, connection mirroring is based on traffic groups, so that an active traffic group can mirror its connections to its standby peer on the next-active device, regardless of which device in the device group is the next-active device"
Take a look at the user guide at
I have 6 in one of mine... But that's a production one with standby sites using HAGroups
I have a 4 node cluster with 2x floating traffic groups...
And another 4 node cluster with 1x floating traffic group and 2 of the nodes with non-floating traffic groups hosting APM...
Lots of options. v11 is very flexible. 11.4 is the one you really want though because you can set proper priorities on the traffic groups to decide which order they move between cluster nodes.
Active active is a total pain in the butt to manage and I would avoid it at all costs. It sounds great on paper and to executives, but the daily operation of it would add allot of work to your day.
It would be up to you to manually balance out the load for every virtual address by putting them in different traffic groups. Also, depending on the number of devices you have and the normal load percentage on them, the number of traffic groups might have to be double or more the number of LTMs you have. This is because you may need to split the load from one failed LTM across multiple devices that are in standby for those traffic groups.
Let's say you have 3 devices running at 55% load each. If one LTM fails then another device will pick up the traffic group and that device will be running at 110%. So in that case you need 6 traffic groups so that a failure of one device would split the load of two traffic groups (27.5% each) across the remaining devices so that each would have 82.5%.
Not a whole lot of fun in my opinion.
You can have up to 8 devices in a sync-failover Device group. They can all be active for traffic groups and be standby for other traffic groups too.
You can have active/active between DCs, as long as the routing is sufficiently in place.